No not really Kay, there are many of us who do not have an aerator and also have frozen ponds, snow covered and all, our fish do fine. Think of it, how many people have aerators on the millions of ponds in the U.S. and Canada. Not many, and those of the majority, do not have fish kills, not big ones anyway. So your answer, in my opinion is, Don't worry about it for now. If you have weeks of no sun light penetration, then you might have a reason to be concerned. Fish are cold blooded, and when temps. drop into the freezing range they become almost dormant, and don't need as much food or oxygen. They adapt.
